Authorities: NM teen planned Wal-Mart shootings

Nehemiah Griego, 15, is seen in an undated photo provided by the Bernalillo County Sheriff's Deptartment. Griego is charged with killing five family members on Jan. 19, 2013, including his father, mother, and three youngest siblings in Albuquerque, N.M. Authorities in New Mexico say Griego had reloaded his guns after the attacks and planned to go to a Wal-Mart and randomly shoot people. Instead, they say he texted a picture of his dead mother to his 12-year-old girlfriend, then spent much of Saturday with her. The two went to the church where his father had been a pastor, and Griego eventually confessed to killing his parents and three younger siblings. (AP Photo/Bernalillo County Sheriff's Deptartment)
— AP

Nehemiah Griego, 15, is seen in an undated photo provided by the Bernalillo County Sheriff's Deptartment. Griego is charged with killing five family members on Jan. 19, 2013, including his father, mother, and three youngest siblings in Albuquerque, N.M. Authorities in New Mexico say Griego had reloaded his guns after the attacks and planned to go to a Wal-Mart and randomly shoot people. Instead, they say he texted a picture of his dead mother to his 12-year-old girlfriend, then spent much of Saturday with her. The two went to the church where his father had been a pastor, and Griego eventually confessed to killing his parents and three younger siblings. (AP Photo/Bernalillo County Sheriff's Deptartment)
/ AP

Bernalillo County Sheriff Dan Houston prepares for a news conference at the sheriff's headquarters in Albuquerque, N.M., on Tuesday, Jan. 22, 2013, regarding the shooting deaths of five family members over the weekend. Authorities have charged Nehemiah Griego, 15, with murder and child abuse counts in connection with the slaying of his family. (AP Photo/Susan Montoya Bryan)— AP

Bernalillo County Sheriff Dan Houston prepares for a news conference at the sheriff's headquarters in Albuquerque, N.M., on Tuesday, Jan. 22, 2013, regarding the shooting deaths of five family members over the weekend. Authorities have charged Nehemiah Griego, 15, with murder and child abuse counts in connection with the slaying of his family. (AP Photo/Susan Montoya Bryan)
/ AP

Bernalillo County District Attorney Kari Brandenburg answers questions during a news conference in Albuquerque, N.M., on Tuesday, Jan. 22, 2013, about the potential legal aspects in the case of a 15-year-old boy who is accused of gunning down his family. Nehemiah Griego remained in custody Tuesday on counts of murder and child abuse resulting in death. (AP Photo/Susan Montoya Bryan)— AP

Bernalillo County District Attorney Kari Brandenburg answers questions during a news conference in Albuquerque, N.M., on Tuesday, Jan. 22, 2013, about the potential legal aspects in the case of a 15-year-old boy who is accused of gunning down his family. Nehemiah Griego remained in custody Tuesday on counts of murder and child abuse resulting in death. (AP Photo/Susan Montoya Bryan)
/ AP

Bernalillo County Sheriff Dan Houston, right, and Lt. Sid Covington answer questions about the shooting deaths of five family members during a news conference at the sheriff's headquarters in Albuquerque, N.M., on Tuesday, Jan. 22, 2013. Authorities have charged Nehemiah Griego, 15, with murder and child abuse counts in connection with the slaying of his family. (AP Photo/Susan Montoya Bryan)— AP

Bernalillo County Sheriff Dan Houston, right, and Lt. Sid Covington answer questions about the shooting deaths of five family members during a news conference at the sheriff's headquarters in Albuquerque, N.M., on Tuesday, Jan. 22, 2013. Authorities have charged Nehemiah Griego, 15, with murder and child abuse counts in connection with the slaying of his family. (AP Photo/Susan Montoya Bryan)
/ AP

This undated photo provided by Eric Griego shows Nehemiah Griego. Griego is charged with killing five family members, including his father, mother, and three youngest siblings in Albuquerque, N.M. Authorities in New Mexico say Griego had reloaded his guns after the attacks and planned to go to a Wal-Mart and randomly shoot people. Instead, they say he texted a picture of his dead mother to his 12-year-old girlfriend, then spent much of Saturday with her. The two went to the church where his father had been a pastor, and Griego eventually confessed to killing his parents and three younger siblings. (AP Photo/Courtesy of Eric Griego)— AP

This undated photo provided by Eric Griego shows Nehemiah Griego. Griego is charged with killing five family members, including his father, mother, and three youngest siblings in Albuquerque, N.M. Authorities in New Mexico say Griego had reloaded his guns after the attacks and planned to go to a Wal-Mart and randomly shoot people. Instead, they say he texted a picture of his dead mother to his 12-year-old girlfriend, then spent much of Saturday with her. The two went to the church where his father had been a pastor, and Griego eventually confessed to killing his parents and three younger siblings. (AP Photo/Courtesy of Eric Griego)
/ AP

ALBUQUERQUE, N.M. 
For at least a week, authorities say, 15-year-old Nehemiah Griego had been planning the attack.

After shooting his mother and three siblings in their beds, he ambushed his father as the pastor returned home from an overnight shift at a homeless shelter. Then the teen reloaded the family's rifles.

His plan was to randomly shoot people at a Wal-Mart on Saturday, which happened to be "Guns Across America" day, until he could be killed in a shootout with law enforcement, according to authorities.

He also contemplated killing his 12-year-old girlfriend's parents, Bernalillo County Sheriff Dan Houston said Tuesday.

And while Griego loaded guns and ammunition into the family's van, Houston said, it was unclear whether the teen did go to a Wal-Mart or how seriously he contemplated continuing his rampage on the same day that thousands of gun advocates gathered peacefully at state capitals around the country to rally against stricter limits on firearms.

The "Guns Across America" events were held after President Barack Obama unveiled a sweeping package of federal gun-control proposals.

What authorities know, the sheriff said, was that Griego texted a picture of his dead mother to his girlfriend, then spent much of Saturday with her and her family, authorities said. That evening, he went to the church where his father worked and confessed to killing his parents and three younger siblings, authorities said.

The sheriff said he didn't know if Griego's contact with his girlfriend avoided further bloodshed. But he said she apparently knew what had happened, and officials were investigating whether she should be charged with failing to report the crime.

"We know Nehemiah had been contemplating this for some time," Houston told reporters at a news conference. Griego apparently had told others of his plans, but whom and when were still under investigation, Houston said.

The motive, Houston said, "was purely that he was frustrated with his mother. He did not give any further explanation."

The teen waived his right to arraignment in adult criminal court Tuesday on charges of murder and child abuse resulting in death and was ordered held without bond. He was arrested Saturday at his family's home in a rural area southwest of Albuquerque.

The sheriff's office identified the dead as Greg Griego, 51, his wife, Sarah Griego, 40, and three of their children: a 9-year-old boy, Zephania Griego, and daughters Jael Griego, 5, and Angelina Griego, 2.

According to Houston and charging documents, it began early Saturday at the family's home, when Nehemiah Griego acted on what he described to investigators as homicidal and suicidal thoughts.

Houston said the teen shot her as she slept at about 1 a.m. with a .22-caliber rifle the parents kept in a closet. He said he killed his siblings and then grabbed his parents' .223-caliber rifle and waited downstairs to ambush his father as he returned from work around 5 a.m.

Griego told authorities he then reloaded the two guns and put them in the family van. Houston said officers found the rifles, as well as at least a dozen rounds for the .22 and a handful of rounds for the other rifle, in the van.